Fork lift attachment for a crane



June 21, 1960 R. F. M CUNE FORK LIFT ATTACHMENT FOR A CRANE Original Filed Sept. 15, 1954 2 Sheets-Sheet 1 INVENTOR. ROBERT F MC CU/VE ATTORNEYS June 21, 1960 R. F. M cUNE FORK LIFT ATTACHMENT FOR A CRANE 2 Sheets-Sheet 2 Original Filed Sept. 15, 1954 INVENTOR. ROBERT F MC CUNE ATTORNEYS United States Patent FORK LIFT ATTACHMENT FOR A CRANE Robert F. McCune, Apt. 405, 3495 Mountain St. Montreal, Quebec, Canada 3 Claims. (Cl. 214-671) This invention relates to lift devices and more particularly to material lift attachments for use with power cranes.

There are many self-propelled lifting vehicles in the prior art, e.g., fork lift trucks and the like, but the constructional features of the device have generally limited the machines to factory or local use. Conventional lift trucks are heavy, small-wheeled devices which are not suitable for use on other than hard-surfaced travelways, and are, furthermore, limited in lifting height. Such trucks are normally considered local trucks, and are not completely mobile. The original cost of such spe-' c-ialized lift trucks prohibits their use in industries, such as the construction trade, where a substantial capital outlay is required in digging and related equipment. A conventional lift truck would not be satisfactory for such a trade since the device is not completely mobile and is not usable in rough terrain where the construction industry is normally engaged in a considerable portion of work. In any type of building construction, a certain amount of material lifting is necessary, but in multiple store units, material handling is actually a major problem.

, The present invention provides a lift attachment for a power crane which is economical and is easily and quickly attached to a crane. The lift attachment is adaptable as a platform, fork, or other type of lift so that it is a versatile and useful device. The device, furthermore, provides a high lift machine which bridges the gap between low building requiring no elevator, and high buildings having a construction elevator as part of the construction. framework. The majority of contractors in the building trades own, or at least have access to, a power crane for digging and similar purposes. Most such power units are readily convertible to a boom-type crane to which the lift attachment of the present invention may be secured. The lift attachment is adapted for connection to the boom head shaft of the boom, and the main hoist cable is secured to the elevating platform to provide a great lifting power for the attachment.

.In conventional building construction, the actual hoisting of material, for example, to the second story of a building, consumes only a minor part of the working day. The device of the invention, being quickly and easily attachable to a boom crane, may be used intermittently throughout the day as required. The lift may be at tached and the lifting requirements for a period of time may be performed. When the necessary lifting has been performed, the lift may be detached and the crane used for other purposes. In such a manner, the lift attachment provides another use for the crane, and provides an economical lift for the construction. The device is very economical in relation to the height of lift.

In general, the lift attachment of the present invention includes a pair of guide rails which are supported in a parallel spaced relation by frame members. The device is attachable to the boom head of the crane boom, and means are provided to support the rails in a generally vertical position. The main hoist cable of the crane,

passing over a sheave on the boom head, is used to provide motivating power for the lift platform. Conventional reeving is used to hold the boom and provide a haul or hoist cable. A carriage rides in the rails, and a platform is connected to the carriage to provide means for holding the material for lifting.

Included among the objects and advantages of the' present invention is a lift device which is an economical and efficient lift attachment for a boom crane and which is quickly and easily secured to the crane. The device provides a mobile lift unit providing a high lift, elficient unit at considerably less capital outlay than normal lift devices.

The invention may be more readily understood by referring to the following detailed description and appended illustrations, in which:

Figure l is an elevational view of a device according to the invention, secured in operative position on a boom crane;

Figure 2 is a front elevation of the lift attachment of the invention;

Figure 3 is an elevational view taken along line 33 of Figure 1 showing an attachment of the lift to the boom head;

Figure 4 is a side elevational detail view of one means for securing a lift attachment to the boom head;

Figure 5 is a detail view of a carriage placement within the guide rails and the platform carried by the carriage; and

Figure 6 is a top plan view of the carriage and guide rails with the attached lift platform.

The completed assembly, illustrated in Figure 1, comprises a lift attachment, shown in general by numeral 10, is secured to the boom head, shown in general by numeral 12, and is maintained in a substantially upright position by means of a jack or stay 14 secured between the crane and the lift attachment. A platform unit 16, secured to a wheeled carriage unit 18, rides the rails and provides means for holding the material to be lifted. A main haul-back cable 20 of the crane passes over a boom head sheave and is secured to the carriage 18 for hoisting and lowering the carriage. The lift attachment is made of a height to be accommodated by the length of a boom 15. A particular boom, of course, may be adapted to utilize numerous sizes of lift attachments by raising and lowering the boom in its are from the power unit 11. The boom is controlled and moved by means of boom cable 21, and the boom cable also holds the boom and the lifting attachment in correct alignment.

By changing the boom angle, onesize of lift attachment will be usable with various sizes of boom cranes. For example, if the lift attachment is twenty-five feet long, the attachment will stand approximately twentyfive feet above the ground. To accommodate an at tachment of this height, a twenty-five foot boom is used. The boom has acenter of rotation several feet above the ground due to the attachment of the boom to the'rotatable power house on the truck, and the boom head, therefore, will stand considerably above the twenty-five feet in vertical position. The twenty-five foot boom, however, will have its boom head about twenty-five 'feet above the ground at a boom angle of about fifty-five degrees angle from horizontal. have its boom head about twenty-five feet above the ground at approximately forty-seven degrees boom angle, and a thirty-five foot boom will have its boom head about twenty-five feet above the ground at approximately thirtyfour degrees boom angle. Thus, it is obvious that by moving the boom to various angles, a single lift attachment is useful for various boom lengths. This feature provides further economies since the lift attachment does Patented June 21, 1960 A thirty foot boom will 3 nothave to .be made specifically for a particular crane and boom size.

The lift attachment comprises a pair of rails 30 and 31 spaced'apart by .means of frame piece 32 and secured by brace members 133.1 The rails are channel members with the :open .Us facing each other. 'The wheels of the carriage ride in the channels bearing on the webs. The lift attachment may be made to .reston the ground or be suspended from the boom head, depending on the use to which the device is to be put. Where the hauling load is light, the lift attachment may be suspended from the boom head, with the bottom above the ground, so thatthe device is mobile and maybe movedsubstantially at will withoutregard tohaving a solid base for the lift attachment. i

The lift attachment is journalled to the boom head shaft 35 by means of a pair ofbearings 36 which are secured to a cross member brace '34 at the top of the liftunit. The journal bearings 136-are placed over the free ends of the boom head shaft 35. Thissystem provides a quick and easy attachment for the lift unit without substantial modification of standard boom head. Other connections may obviously be used, especially where the lift attachment is not to be secured directly'to the boom head but'to a lower section of the crane boom. The lift attachment may also be held by the boom cable without attachment to the boom head, in which case the journal bearings are not necessaryjbut ahigher brace or support, such as 14, may be used, if desired, to hold the upper portion of the lift steady.

1 The carriage comprises a frame 18.,havingan upper shaft 4%) and a lower shaft 41 journalled therein. Wheels or main rollers 42 are securedtothe upper shaft 40, and Wheels 43 are securedto the'lower shaft 41. The wheels 42 and 143 are adapted. forriding in the channels 30 and 31. The face of the Wheel is. sloped to correspond to the slopeof theweb of the channel for providing a full hearing surface of the Wheel against the web channel. Guide rollers 44 are secured to the upper frame portion and are positioned-to ride the channel web adjacent the platform side of the carriage. Lower guide rollers 45 are, likewise, secured to the lower'frame portion. The guides prevent'rubbing of the carriage against the channel rails on any lateral or sidewise movement. The two systems of rollers, including the upper-main roller 42 and lower main roller 43, and the upper guide roller 44 and the lower guide roller 45, provide the bearing surfaces of the carriage on the guide rails. .The main rollers carry the main hearing load of'the carriageon the rails. A weight on platform 16 tends to rotate the carriage about its horizontal axis forcing the upper :main roller against the front web and the lower main roller against the back Web. Any sideways .or lateral movement of the carriage is carried by the guiderollers 44'and 45 against the edge of the web. Lock members 46, secured to each guide roller shaft, prevent accidental removal of the carriage from the rollers. The loclcmembers provide a safety feature for the carriage.

The platform 16 is illustrated as a fork lift platform, however, it is obvious that'a solid platform or other types of platform may be utilized with the lift. With the lift attachment secured to the boom head and not resting on the ground, the crane and lift attachment combination can be used as a large size fork lift truck. In such a use, the unit provides an additional advantage of having a lift platform which is rotatable around a pivot point. In other words, the lift attachment may be rotated about the axis of the power cab of the power crane as well as being moved around bythe truck.

In operating the device of the present invention, the

.4 lift attachment is placed in position for attachment tothe boom head of the crane. .The top portion of the lift attachment is secured to the boom head by placing the bearings 36 over the free ends of the boom head shaft 35. Under normal circumstances the lift attachment will be in a substantially horizontal position on the ground so that theboom of the crane will have to be lowereddown to the attachment and the connection made at that level. The crane isthen raised to uppermost position pulling the lift attachment into upright position. The stabilizer 14 is then attached to the lift attachment and he crane to provide a'substantially verticalposition for the cran'e. The main haul-back cable is then secured to an eye 47 on the carriage. One simple connection between the carriage and the cable is a hook on the main hoist cable placed in the eye 47. It is obvious that other types of connection can be utilized depending on the use required for the lift attachment. Withthe lift attachment in position on the boom crane and placed a distance above' the ground, the device makes a mobile, efficient elevating or hoisting device.

I The stabilizer or stay is an adjustable member forattaching between the crane turn table and the rail frame. Such a unit may be hydraulic, or pin-held extensible rod, or other extensible means for maintaining the liftin a substantially vertical position. Also, other types of rail members, or carriage members,.etc., may be changed Without departing from the spirit and the scope of the invention.

I claim:

I. A lift attachment for a mobile boom crane which includes a pivotal elongated boom extending-from the movable portion of the turntable mounted on a prime mover comprising a rectangular frame having 'a pair'of facing longitudinal channels extending along the-sides thereof, a mount at the upper endof said frame inclusive of bearings arranged to engage a pulley shaft atthe boom point of the crane, said frame arranged to hang substantially vertically from the boom point of the crane, a carriage inclusive of main guide rollers and lateral guide rollers mounted and cooperative with said channel for reciprocal movement along the frame, means for attaching the haul cable from the boom point of the crane to said carriage, platform means extending outwardly from said carriage, and means interconnecting said frame with the swing table of the crane for maintaining the frame substantially vertically during lifting movements of said carriage and swinging movements of the swing table.

2. A lift attachment according. to. claim 1 in which-the main guiderollers of thecarriage are mounted between the flanges of the channels, and the guide rollers :are mounted on one of said flanges for preventing lateral movement of the carriage.

3. A lift attachment according toclaim 1 in which the means interconnecting the swing table and said frameineludes an extendable jack for varying the distance between the frame andthe'swing table so as to maintainthe position at variable posi-;

frame in substantiallyvertical tions of the boom.

References Cited in-the' file of this patent UNITED STATES PATENTS 1,539,344 Adam May,26, .1925 2,241,275 Shinn et al. May 6, 1941 2,342,934 'Grundon et al Feb. 29, 1944 2,490,198 Boone 'Dec.v 6, 1949 2,505,009 Schroeder Apr. 25, 1950 FOREIGN PATENTS 697,777 Great Britain Sept. '30, 1953 feaarm 4 

